Hi, I just acquired an HP25 calculator. It's in mint physical condition but I can't seem to remove the rear battery cover. Either I'm doing something wrong or there is a corrosion issue. Any suggestions? Thanks.

The door is really the top of the battery pack, which you remove by sliding it forward towards the bottom of the calculator and then pushing down to release the rear of the pack. The battery cells are spring loaded and the springs should compress to allow the pack to slide forward when you push on it.

Is it possible for you to contact the seller about this? Sometimes these battery packs are rebuilt by splitting the case and then gluing it back together, such that the pack is slightly thicker and becomes a very tight fit in the calculator. I have a few that are a bit tight and require a bit of force to open, however, I've always been able to open them without resorting to prying, which will cause some cosmetic damage.

Pop out the top two rubber feet and remove the two Phillips screws underneath. Now, with the same Phillips you removed the screws with, push on either one of the two charger input pins and push the keyboard assembly out at the top. Now you can lift the electronics up and out leaving you with the battery and case back as one piece. Once that is complete, you can easily remove the battery.

I've opened plenty of Woodstock cases with the battery pack removed, but never with one installed. Wouldn't the pressure of the battery terminals against the pcb contacts prevent you from separating the keyboard assembly from the case and battery pack?